Engine/Transmission (1998.5 - 2002) lift pump pressure question

[Oliver88]

My 99 runs around 9-10 psi on my autometer gauge. (If my memory is correct I think it ran higher in the past) Sometimes it drops to near 6 psi while towing at WOT. Is it time for a new lift pump? Do they fail gradually or all at once? Where is the best place to pick one up? Thanks for the advice.

Greg

 

[PC12Driver]

Sounds like it's getting tired, especially if the truck is stock. Mine started getting weak, so I replaced it thinking death was immenent. Some folks have had them just quit. I got mine at the local Peterbuilt dealer for $135 (that was straight from Cummins; much cheaper than the Dodge dealer).

 

[Fireman Dave]

I agree - sounds like it's starting to go. I think anything under 8 at WOT is a warning sign. My first one went gradually, but I've heard of others going suddenly too. I just ordered a spare from here: http://www.hoeslidiesel.com/specials.htm



My pressure is a little sporatic lately, so I don't want to get stranded.

 

[DCutler]

I am on my second one, now and it is getting weak, I just orderd a FASS system 150 gph and its here it will be on this weekend YEEEHAAa !! no more lift pumps, it does sound like it is going out, I dont know how your budget is but I would recommend one !!

 

[Shelton]

Sounds just like mine over the last three or so months. Prior to that was a fairly steady 12 at idle and 9 at cruise, then dropped to 9 at idle and 6 at cruise. Changed filters last weekend and took a lot more work than usual to get it primed. Picked up a new pump from Cummins and pressures are now 14 at idle, 12 at cruise, and 10 at WOT.

 

[BILLYGEE]

Won't Be Long!

It won't be long and I'll bet a few of you will see the old P0216 code if it isn't stored i :{ n there already and before too long time for a new VP-44. Been there done that... today as a matter of fact. Truck at the dealer as we speak. Lift pump and injection pump being replaced under warranty.

 

[Oliver88]

Well, the budget never seems to be where is should, but if you need a lift pump it beats buying an injection pump. Thanks for the help guys.

Greg Davis

 

[RJPotts]

I'm having similar issues, finally got my gauges in, all mechanical, everything seems right but the fuel pressure.

It sits right at 10psi all the time, its gotten to 12 once, doesn't drop when I get on it, doesn't go up at idle, just sits there at 10psi.

I have the fuel isolator and I'm assuming air bubbles in the line are the reason, does this sound right or is my LP on its way out too?

-R. J.

 

[Walt-L]

My OEM lift pump has over 4K on it and mine reads a bit over 14 at idle about 13 cruising at 60-65 and 10. 5 WOT. I mounted the LP down on the frame with all straight -AN6 fittings. (no banjos).

 

[Fireman Dave]

It sits right at 10psi all the time, its gotten to 12 once, doesn't drop when I get on it, doesn't go up at idle, just sits there at 10psi.

I have the fuel isolator and I'm assuming air bubbles in the line are the reason, does this sound right or is my LP on its way out too?

-R. J.

If you don't see any movement with the throttle, something's wrong with your gauge setup. You're not getting an accurate reading. Your gauge should be very responsive in relation to the throttle position.

 

[Oliver88]

Wow! I installed the lift pump and boy did that make a difference in fuel pressure. Now I have almost 15 psi at idle and can't get it under ten at WOT. It sure beats the 9-12 psi at idle and sometimes near 6 at WOT towing. It was not a bad install at all.

Thanks for the advice.

Greg

 

[JCutter]

Where is the best place to mount the pressure guage hose at, on the injuction pump or the on the pre-filter side. I had it on the pre-filter side and was seeing 14psi and 5 psi at WOT. I then placed it just before the injection pump and saw 12psi and 0 at WOT :--) . It has 98,000 and never had the filter changed , new filter and drilled banjo's im seeing 12-13 idle and about 8 WOT at the injection pump.



Just wandering where everybody has theirs placed at pre-pump or pre-filter.

 

[JFitzgerald]

I just installed a guage yesterday. I used a Jegs 15 PSI liquid filled guage and an Autometer braided stainless hose kit. I connected at the injection pump's inlet with a tapped banjo bolt. It shows 12-15 at idle, about 12 on a flat steady highway cruise, and the lowest I saw it go under hard throttle (no trailer) was 8 PSI. Should I be concerned, or just keep an eye on it? The truck is at almost 135K.



On another note, I am noticing a light buzz noise directly related to engine load (louder with more throttle). I wonder if it is coming through the firewall where I put the hose through, or if it is the guage pulsing. With the liquid filled guage, I can just barely see fluctuation in the needle. I used a rubber grommet in the firewall and tried to replace as much of the insulation as possible. Or is this normal with the mechanical guage?

 

[Oliver88]

My guage sending unit is on the fuel filter.

Greg